Subaru Seminars



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The Subaru Seminar is usually held in Room 104 of the Hilo Base Facility, adjacent to the main lobby. Everyone is welcome to attend. If you are interested in giving a seminar, please contact Subaru seminar organizers (Tae-Soo Pyo, Sherry Yeh, Nagayoshi Ohashi) by email : (please change"_at" to @).

August 04, Tuesday, 11:30 am in 104

" Spatially resolved physical conditions of molecular gas: a zoom-in from circumnuclear region of M83 to Carina nebula "

Ronin Wu

(University of Tokyo)

Since the launch of the Herschel Space Observatory (Pilbratt et al. 2010), our under- standing about the photodissociation regions (PDR) has taken a step forward. In the band- width of the Fourier Transform Spectrometer (FTS) of the Spectral and Photometric Imaging REceiver (SPIRE) on board Herschel, ten CO rotational transitions, including J = 4 - 3 to J = 13 - 12, and three fine structure lines, including [CI] 609, [CI] 370, and [NII] 250 μm, are covered. This presentation focuses on the physical conditions of molecular gas probed by the Herschel SPIRE/FTS. Based on the spatially resolved physical parameters derived from the CO spectral line energy distribution (SLED) map and the comparisons with the dust properties and starformation tracers, I will first present our findings at the circumnuclear region of M83 (Wu et al. 2015), and then zoom in toward the molecular cloud near a young open cluster, Trumpler 14, in Carina nebula. I will discuss (1) the potential of using [NII] 250 and [CI] 370 micron as starformation tracers; (2) the reliability of tracing molecular gas with CO (3) the excitation mechanisms of warm CO (4) the possibility of studying stellar feedback by tracing the thermal pressure of interstellar molecular gas.

" Edge Structure Variations in Interstellar PAHs "

Mark Hammonds

(University of Tokyo)

Polycyclic aromatic hydrocarbons (PAHs) are expected to contain a significant percentage of the carbon budget of the galaxy, and their mid-infrared emission bands are among the strongest and most prominent features in the entire galactic SED. These bands appear sensitive to local environmental conditions, with many specific emission bands showing significant variation in peak wavelength, line profile, and intensity. Understanding the precise reasons behind these variations may allow the use of PAH emission bands as a powerful diagnostic tool for interstellar environments. However, the exact structures and morphologies of PAHs observed astronomically are unknown and poorly understood. The work presented here attempts to decompose two regions of the PAH infrared spectrum, the 3-4 μm range, and the 11-14 μm range, both of which are due to vibration of C-H bonds and are therefore diagnostic of PAH edge structures. Analysing data from AKARI IRC, the strong 3.3 μm emission band is confirmed to be composed of two underlying sub-features at 3.28 μm and 3.30 μm, arising from bay and non-bay sites on PAHs. The remaining emission from 3.4-3.6 μm is also decomposed and contributing factors are discussed. These data are compared with coincident ISO SWS observations from 11-14 μm, diagnostic of the number of hydrogen atoms attached per aromatic ring. Results are discussed in terms of PAH morphologies and molecular stability, together with implications for related unsolved problems in astronomical spectroscopy, the diffuse interstellar bands (DIBs) and anomalous microwave emission (AME).

Seminars are also held at JAC, CFHT, and IfA.

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